About Primula - Lab Report Example

Lab Report about Primula This paper is involves a lab report about Primula vulgarisflower. The report entails the structure and functions of the flower. The Primula vulgaris flower is a flower species within the family known as Primulaceae. The flower is native to both western and southern parts of Europe, northwestern part of Africa, and southwest of Asia. The flower is commonly referred to as primrose. The lab practical was done using the pin and thrum dimorphic flowers of the flower species. It was initiated to study the flower parts in terms of their structure and function. The study related floral structure the reproductive strategies. The practical aimed at documenting the observations accurately and developing meaningful observational skills. To achieve the practical objectives, a dissecting microscope and a compound microscope were used to compare the pin and thrum parts of the flower in a morphological manner. Again, collection of measurements was done to evidence the dimorphism. In the practical, it was established that the two flower forms are significantly different in their morphological structures. Their differences are readily visible through the size and structure of their styles, anthers, petals, and other aspects as seen in this lab report. Introduction Primula vulgaris is one of the largest and commonest genera of the Primulaceae and is mainly centred in temperate regions especially the mountainous areas within the northern hemisphere. The pollination of the flower is usually aided by human activities that promote insect pollination. In this case, insect pollinators visiting the flowers to look for nectar help in the pollination process. The species flowers are known by dustily that is mainly characterized through the development of pin flowers that are long and styled. These flowers also have anthers that head midway down flower’s corolla tube as well as some short-styled thrum flowers that have anthers positioned at the corolla-tube’s mouth (Webb & Lloyd, 1986). Typically, heterostyly is a common feature for the Primula genus whereby most of the species are distylous according to Richards (1993). The pollen morphology of all species has been previously investigated, but there are no surveys related to the Primula vulgaris species have ever been found. This argument provides that only a close investigation of the Primula vulgaris would provide a better understanding of the reproductive biology of the species reproduction biology. With regard to this species, most of its flowering plants have been found to be hermaphrodite whereby they contain both the male and female reproductive organs. Nevertheless, plants are generally different from animals whenever it comes to reproduction since due to their stationary nature; they have to develop various out-breeding strategies. Some plants would develop male and female flowers on different plants of the same species while others are found to have separate female and male flowers within the same plant. Within the Primula vulgaris, like in many plants, self-pollination is prevented through different time of maturation between the female and male flowers. The flowers of this species mostly employ a reproduction strategy that encourages cross-pollination and outbreading. Methods The practical was executed in three parts. These parts were named as part 1, part 2 and part 3. In part 1, flowers were provided to the practical benches from which students have to look at the flowers closely. Two types of flowers were provided. From the two flowers that were provided, each form of flower was selected for further analysis. A pin-form flower and a thrum-form flower were dissected carefully. The observations made in this part were drawn on a plain separate piece of paper. In this case, the floral structure of each form was drawn ensuring an entire page for each flower form. In each of the two drawings, various floral parts were labelled with a clear indication of every part’s function. A scale bar was then provides and a working for the drawing magnification was done as well. Part 2 of the practical involved collecting class data for the two distinct morphological features. These features were from the pin and thrum flowers concurrently. To come up with the data, each student had to dissect the gunoecium, specifically from the pin flowers as well as the thrum flowers. The style length in each form of flower was then measured. The measurement was done in millimetres and it was initiated from the ovary top to the stigma’s base. The activity step in this part entailed dissecting petals from the pin flowers and the thrum flowers after which their length measurements were taken. In each activity, every student collected his/her bench data. One student was asked to contribute the data to generate the class total on the class white board. Part 3 involved the investigation of further morphological differences between the pin flowers and thrum flowers. In this part, observation skills and investigative skills were applied in looking for the additional differences. The major aspects considered here were stigma surfaces, style surface, and pollen grains (Lecture Outline, 2010). Results The practical results indicated two forms the Primula vulgaris species of different style length. These two forms included the long-styled flower and the short-styled flower (Webster & Gilmartin, 2006). In the comparison the pin form and the thrum form in terms of anther position, the anther position was found to be higher in the thrum form than in the pin form. The style length was conversely found to be shorter in the thrum form than in the pin form. The stigma of the pin-form flower is positioned above the anthers while the stigma of the thrum-form flower is positioned below the anthers. The Collected data was tabulated to ensure both appealing appearance and clarity. This was done based on the total averages for each measurement. The results were as follows: Table 1: Data about the Pin-form and the Thrum-form Flowers Pin Thrum Style length (mean + SD in mm) Anther position (mean + SD in mm) Style length (mean + SD in mm) Anther position (mean + SD in mm) 9.67± 0.20 6.51± 0.21 6.96±0.16 7.56 ± 0.11) Table 2: Petal Length Pin Thrum Petal length (Mean + SD in mm) Petal length (Mean + SD in mm) 11.41±0.31 12.26±0.43 Table 3: Stigma Surface Pin Thrum Stigma Surface (Mean + SD in mm) Stigma Surface (Mean + SD in mm) 0.51 ± 0.06 0.36 ± 0.03 Table 4: Style Surface Pin Thrum Style Surface (Mean + SD in mm2) Style Surface (Mean + SD in mm2) 2.0 ± 0.2 3.3 ±0.5 Table 5: Pollen Grain Volume Pin Thrum Pollen Grain Volume (Mean + SD in mm3) Pollen Grain Volume (Mean + SD in mm3) 0.023±0.001 0.023±0.001 While the pin-form flower and thrum—form flower show significant differences in terms of lengths of the styles, stigma length and surfaces, petal sizes, and pollen grain volume, most of the differences are not readily visible. The major difference could be seen in the styles of the two flower and the petals. The pin style is physically different because it forms a column within the flower centre with the flower stigmas facing outside. Contrary, the styles of the thrum-form flowers spread outwards, almost appressed to the wall of the flower corolla, and its tips extend up the petals by almost a third way up. The stigma in this case faces inwards. On the other hand, the petals of the pin-form flower are much less than the petal of the thrum-form flower. Discussion Typically, two flower forms of the Primula vulgaris species exist with different style lengths as well as anther positions. Another distinguishing feature in the two forms of flowers from the same plant species is the variation in pollen dimensions, the diameter of lumina reticulum, and variation in the number of colpi. The pollen grains radially symmetric, isopolar, and more importantly, they range from small to medium. They also depict different sizes between the pin and the thrum flower forms (Webb & Lloyd, 1986). The pollen grains of the thrum flower are larger than the pollen grains of the pin-form flower by about 50 per cent. This is however not always the case since the same species has equal pollen grain diameters in the two forms for the polar Primula vulgaris plant species. The diameter ratios in this case are similar and the two forms of pollen grains depict the same shape. Regarding the differences evidenced in the two flower forms, the development of cells generates the variations between the pin-form flower and the thrum-form flower. Previous studies have depicted longer cells in the pin-form style as well as pin flower’s longer stigmatic papillae than in the case of the thrum (Webster & Gilmartin, 2006). Stigmatic length of the papillae is correlated with style cell length (Richards, 1993). A mutation process has also been evident to reduce the style cell length thereby leading to a shorter stigma in the thrum. This mutation also leads to a stigma that is positions below the anthers in the thrum. The longer cell in the style of the pin-form flower contributes to longer style than in the thrum flower. Consequently, the longer style in the pin-form flower leads to a shorter based corolla, which makes the corolla size in the pin flower shorter than the corolla size in the thrum-form flower. The morphological structure could contribute to a coordinated transfer of pollen between the two morphs especially given that the pollen grains in the two cases have been found to be equal in size. Conclusion It can be concluded that the pin-form flowers have longer but narrower styles than the thrum-form flowers, which have shorter and broader stiles. The pin-form flowers on the other hand have smaller petals than the thrum-form flowers. Given the structure of the two flower forms, self-pollination is likely to occur in the thrum-form flower, where the stigma is in a lower position than the position of the anthers. Nevertheless, the arrangement is in such a way that there is some possible coordination of pollen deposition in the two flower forms. Pin flowers may tend to be sending pollen to the stigma of the pin followers and vice versa. The transfer dynamics of pollen between the two flower forms could otherwise be complicated. Bibliography Lecture Outline, 2010. Campbell Biology, 8th edition. Ch 38: Angiosperm reproduction & biotechnology. Pearson. Li, J., A.Webster, M., Smith, M. C. & Gilmartin, P. M., 2011. Floral heteromorphy in Primula vulgaris: progress towards isolation and characterization of the S locus. Annals of Botany, Volume 108, p. 715–726. Richards, J., 1993. Primula. 1st ed. Portland, Oregon, USA: Timber Press. Webb, C. & Lloyd, D., 1986. The avoidance of interference between the presentation of pollen and stigmas in angiosperms II. Herkogamy. New Zealand Journal of Botany, Volume 24, pp. 163-178. Webster, M. A. & Gilmartin, P. M., 2006. Analysis of late stage flower development in vulgaris reveals novel differences in cell morphology and temporal aspects of floral heteromorphy. New Phytologist, 171(doi: 10.1111/j.1469-8137.2006.01719.x), p. 591–603. Read More